The present invention relates to a power drive system for driving a sliding door in movement between an open and a closed position. It is particularly directed to a drive arrangement which accommodates shifting between manual and positively driven powered operation of the door at any position along its path of movement while incorporating in the power drive a control responsive to an overload to stop the door in the event an object is trapped by the closing door. While useful in other applications, the power drive system of the present invention is especially well adapted for use in operating the sliding door of a van type vehicle.
All power drive systems for sliding doors require a power system capable of driving an output member coupled to the door to drive the door in either direction over a relatively long working stroke, and for optimum control of the door movement, a positive mechanical interconnection between the motor and door operable in either direction of movement is required. In addition to the foregoing considerations applicable to sliding doors in general, further problems are presented where the drive is to power the sliding door of a van.
In the van application of the power drive system the sliding door is conventionally mounted at the passenger side of the van and a major convenience of the system is that it may be power operated by control switches accessible from the drivers seat. However, if the driver is outside the van loading or unloading articles through the sliding door, the power controls are out of reach and there are many occasions where in this situation, the driver will want to open or close the door manually. If the door is positively mechanically linked to the power source of the drive, this connection will interfere with manual operation of the door and, in the case of certain types of control systems, disturb a relationship between the door and drive relied upon by the control system to sense the position of the door along its path of travel.
In addition, for obvious reasons, it is desirable that exposure of the moving parts of the drive system be minimized. Fitting the drive into existing cavities within the vehicle body is a goal which cannot always be achieved.
The drive of the present invention presents a practical solution to the problems discussed above.